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US20140035284A1 - Wind park control system - Google Patents

Wind park control system Download PDF

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Publication number
US20140035284A1
US20140035284A1 US13/951,705 US201313951705A US2014035284A1 US 20140035284 A1 US20140035284 A1 US 20140035284A1 US 201313951705 A US201313951705 A US 201313951705A US 2014035284 A1 US2014035284 A1 US 2014035284A1
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United States
Prior art keywords
reactive power
wind
wind turbines
wind turbine
deliver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
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US13/951,705
Inventor
John Bech
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Siemens AG
Original Assignee
Siemens AG
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Application filed by Siemens AG filed Critical Siemens AG
Assigned to SIEMENS WIND POWER A/S reassignment SIEMENS WIND POWER A/S ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BECH, JOHN
Assigned to SIEMENS AKTIENGESELLSCHAFT reassignment SIEMENS AKTIENGESELLSCHAFT ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SIEMENS WIND POWER A/S
Publication of US20140035284A1 publication Critical patent/US20140035284A1/en
Abandoned legal-status Critical Current

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Classifications

    • F03D9/005
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D7/00Controlling wind motors 
    • F03D7/02Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/028Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power
    • F03D7/0284Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power in relation to the state of the electric grid
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D7/00Controlling wind motors 
    • F03D7/02Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/04Automatic control; Regulation
    • F03D7/042Automatic control; Regulation by means of an electrical or electronic controller
    • F03D7/048Automatic control; Regulation by means of an electrical or electronic controller controlling wind farms
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D9/00Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby; Wind motors specially adapted for installation in particular locations
    • F03D9/20Wind motors characterised by the driven apparatus
    • F03D9/25Wind motors characterised by the driven apparatus the apparatus being an electrical generator
    • F03D9/255Wind motors characterised by the driven apparatus the apparatus being an electrical generator connected to electrical distribution networks; Arrangements therefor
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D9/00Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby; Wind motors specially adapted for installation in particular locations
    • F03D9/20Wind motors characterised by the driven apparatus
    • F03D9/25Wind motors characterised by the driven apparatus the apparatus being an electrical generator
    • F03D9/255Wind motors characterised by the driven apparatus the apparatus being an electrical generator connected to electrical distribution networks; Arrangements therefor
    • F03D9/257Wind motors characterised by the driven apparatus the apparatus being an electrical generator connected to electrical distribution networks; Arrangements therefor the wind motor being part of a wind farm
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/72Wind turbines with rotation axis in wind direction
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/76Power conversion electric or electronic aspects
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30Reactive power compensation

Definitions

  • the present invention relates to the technical field of wind parks.
  • the present invention relates to a control system for a wind park, in particular controlling the reactive power output of each wind turbine in the wind park.
  • Wind parks comprise a plurality of single wind turbines and provide power to a utility grid.
  • Today utility grids require reactive power delivery/consumption from wind power plants or parks.
  • the reactive power may be needed for instance by loads (like electrical motors).
  • Modern wind turbines may be able to control their reactive power output.
  • the reactive power requirement of the utility grid may be fulfilled.
  • a wind park control system for controlling a reactive power output of a plurality of wind turbines of a wind park, wherein the wind park is adapted to deliver active power and reactive power to a utility grid.
  • the wind park control system comprises a determination unit being adapted to determine a total amount of reactive power being required by the utility grid (which corresponds to receiving information from the utility grid being indicative for the total amount of reactive power being required by the utility grid) and being adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver, a calculation unit being adapted to calculate a capability scheme, wherein the capability scheme comprises an order for the plurality of wind turbines according to which order the wind turbines are selected for delivering reactive power, wherein the capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and the total electrical power loss being contributed by each connection of all the wind turbines to the utility grid, and an adjustment unit being adapted to adjust an actual amount of reactive power to be provided by the plurality of
  • a wind park may comprise a plurality of wind turbines for delivering power to a utility grid.
  • a wind turbine may be used for generating electrical power by converting wind into electrical power.
  • wind turbines comprise a tower, a wind turbine rotor, which is arranged at a top portion of the tower and which comprises at least one blade, and a generator being mechanically coupled with the wind turbine rotor.
  • the utility grid may have some requirements, in particular reactive power requirements, which should be fulfilled. These requirements may be provided to the wind park control system, in particular the determination unit.
  • the utility grid may have specific requirements for the reactive power.
  • the requirements for delivery/consumption of reactive power from the wind park or wind power plant may be either reactive power, power factor or voltage control.
  • wind turbines contributing less electrical loss may be preferred for providing or delivering reactive power.
  • the wind turbines may be selected according to the electrical loss they contribute and according to the amount of reactive power they may provide.
  • the wind turbines may be selected in a number or amount sufficient for fulfilling the requirements for reactive power of the utility grid. Thus, the reactive power of the wind turbines may be accumulated.
  • the determination unit and the calculation unit may be integrated as one single unit.
  • the plurality of wind turbines may be at least two wind turbines.
  • the determination unit is adapted to determine the individual amount of reactive power for each wind turbine based on a generated active power and a voltage at the wind turbine.
  • the reactive power each wind turbines is capable to deliver may be determined first.
  • the determination may be based on an actual voltage and an actual active power generated at the wind turbine.
  • the order of the wind turbines in the capability scheme is based on priorities, wherein a wind turbine having a connection with the lowest electrical loss has the highest priority.
  • the wind turbine having the minimum electrical collector network power loss from all the wind turbines may have the highest priority.
  • the capability scheme may comprise a table wherein the wind turbines are arranged in an order corresponding to the amount of electrical loss they are providing.
  • the wind turbine contributing the lowest electrical loss may have the highest priority, wherein a wind turbine contributing more electrical loss may have a lower priority.
  • the determination unit is adapted to determine the electrical losses based on a resistance being provided by the connection and a current being associated with the reactive power of the wind turbine.
  • the electrical loss each wind turbine is contributing may be determined based on characteristics of the connection.
  • Each connection may have a specific resistance.
  • the electrical loss may be calculated by the resistance of the connection multiplied with a current squared, wherein the current may consist of two parts, active current and reactive current.
  • the current may be associated with the reactive power of the wind turbine.
  • the order of the wind turbines in the capability scheme is based on priorities, wherein a priority is associated with the resistance being provided by the corresponding connection such that a low resistance is associated with a high priority.
  • the capability scheme may comprise a table wherein the wind turbines are arranged in an order corresponding to the amount of resistance of the corresponding connection.
  • the wind turbine having the connection with the lowest resistance may have the highest priority, wherein a wind turbine having a connection with a higher resistance may have a lower priority.
  • the determination unit is further adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to consume, and the calculation unit is adapted to calculate the capability scheme based on the determined individual amount of reactive power of each wind turbine, which each wind turbine is capable to deliver and/or consume.
  • the determination unit may also determine the capability of each wind turbine to consume reactive power.
  • the capability scheme may in this case comprise information about the capability of delivering and consuming reactive power for each wind turbine.
  • the adjustment unit is further adapted to adjust the actual amount of reactive power to be provided by the plurality of wind turbines by controlling the reactive power output of each wind turbine based on the calculated capability scheme such that the wind turbines are selected for delivering and/or consuming reactive power to fulfill the determined total amount of reactive power.
  • each wind turbine may also consume reactive power. This may be used for adjusting the reactive power being needed by the utility grid.
  • a wind park comprises a wind park control system having the above mentioned features and a plurality of wind turbines being controllable by the wind park control system.
  • the wind park control system may be located near the wind turbines or may be located remote. Further, the wind park control system may be comprised by single units, each unit being located near a wind turbine.
  • a method for controlling a reactive power output of a plurality of wind turbines of a wind park comprises determining, by a determination unit, a total amount of reactive power being required by the utility grid and determining for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver, calculating, by a calculation unit, a capability scheme, wherein the capability scheme comprises an order for the plurality of wind turbines, according to which order the wind turbines are selected for delivering reactive power, wherein the capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and the total electrical power loss being contributed by each connection of all the wind turbine to the utility grid, and adjusting, by an adjustment unit, an actual amount of reactive power to be provided by the plurality of wind turbines, wherein the reactive power output of each wind turbine is controlled based on the calculated capability scheme wherein the wind turbines are selected for delivering reactive power in
  • a computer program for controlling a reactive power output of a plurality of wind turbines of a wind park the computer program, when being executed by a data processor, is adapted for controlling the method as described above.
  • a computer-readable medium in which a computer program for controlling a reactive power output of a plurality of wind turbines of a wind park is stored, which computer program, when being executed by a processor, is adapted to carry out or control a method as described above.
  • reference to a computer program is intended to be equivalent to a reference to a program element and/or a computer readable medium containing instructions for controlling a computer system to coordinate the performance of the above described method.
  • the computer program may be implemented as computer readable instruction code by use of any suitable programming language, such as, for example, JAVA, C++, and may be stored on a computer-readable medium (removable disk, volatile or non-volatile memory, embedded memory/processor, etc.).
  • the instruction code is operable to program a computer or any other programmable device to carry out the intended functions.
  • the computer program may be available from a network, such as the World Wide Web, from which it may be downloaded.
  • the herein disclosed subject matter may be realized by means of a computer program respectively software. However, the herein disclosed subject matter may also be realized by means of one or more specific electronic circuits respectively hardware. Furthermore, the herein disclosed subject matter may also be realized in a hybrid form, i.e. in a combination of software modules and hardware modules.
  • FIG. 1 shows a wind park comprising a wind park control system according to an embodiment of the present invention.
  • FIG. 2 shows a flow diagram for controlling a wind park according to a further embodiment of the invention.
  • FIG. 3 shows a capability scheme according to an embodiment of the invention.
  • FIG. 4 shows a wind park layout according to an embodiment of the invention.
  • FIG. 1 shows a wind park 100 .
  • the wind park 100 comprises a wind park control system 101 and a plurality of wind turbines 105 , 106 , 107 .
  • the wind park control system is adapted to control a reactive power output of the plurality of wind turbines.
  • the wind park may deliver active power and reactive power to a utility grid (not shown).
  • the wind park control system comprises a determination unit 102 , a calculation unit 103 and an adjustment unit 104 .
  • the determination unit 102 is adapted to determine a total amount of reactive power being required by the utility grid.
  • the determination unit is further adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver.
  • the calculation unit 103 is adapted to calculate a capability scheme.
  • the capability scheme comprises an order for the plurality of wind turbines according to which the wind turbines are selected for delivering reactive power.
  • the capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and an electrical loss occurring due to a connection from each wind turbine to the utility grid.
  • the adjustment unit 104 is adapted to adjust an actual amount of reactive power to be provided by the plurality of wind turbines.
  • the reactive power output of each wind turbine is controlled based on the calculated capability scheme wherein the wind turbines are selected for delivering reactive power in the order of the capability scheme such that the determined total amount of reactive power is fulfilled.
  • FIG. 2 illustrates a flowchart for the function of the wind park control system.
  • An amount of active power from all wind turbines 201 and an amount of voltage at all wind turbines 202 is provided to the calculation/determination unit 203 .
  • the capability scheme is calculated and provided 204 to the adjustment unit 205 .
  • the reactive power deliver from the wind turbines is adjusted according to the capability scheme.
  • a next step 206 it is determined whether the reactive power requirements 207 from the utility grid are fulfilled. If yes, it may be repeatedly determined whether the requirements are still fulfilled. If no, the adjustment may be repeated.
  • the capability scheme may be set up so that the wind turbines that give the lowest losses in the network are used first to deliver/consume the reactive power.
  • the capability scheme comprises information so that the turbines being electrical closest to the connection point of the wind farm/park to the utility grid are first used to deliver/consume the reactive power required by the utility grid.
  • FIG. 3 illustrates an example for a capability scheme according to an embodiment of the invention.
  • the scheme is shown for eight wind turbines. On the x-axis, the numbers represent the wind turbines. On the y-axis, the accumulated reactive power from all wind turbines is shown.
  • the wind turbine 1 is electrical closest to the connection point of the wind farm (i.e., contributes the lowest electrical loss) and then wind turbine 2 is the next and so on up to number 8 .
  • the wind turbine numbers are where the wind turbine is at their reactive power capacity. It may be assumed that each wind turbine can deliver/consume +/ ⁇ 1.0 pu (per-unit) reactive power in this example.
  • wind turbine 1 , 2 , 3 and 4 have to deliver their full reactive power of 1.0 pu and wind turbine 5 has to deliver 0.5 pu. If there is a change in the reactive power requirement, then the control system should follow the curve to have a jumpless transfer between two reactive power setpoints.
  • the curve of FIG. 3 may be generated from information from the wind turbines about their capability to deliver/consume reactive power. This capability may be typically dependent on active power generated and voltage at the wind turbines. The active power and voltage from each wind turbine may be send to the determination/calculation unit, which then calculates the capabilities for deliver/consume reactive power.
  • the electrical losses in the wind farm network are related to the resistance time the current squared.
  • the current may consist of two parts, one is active current and the other is reactive current.
  • One idea of the present system is to prioritize the reactive current. This means that the reactive current may run through a minimum if resistance.
  • the control system may follow the line of FIG. 3 to give a jumpless transfer between two reactive power setpoints.
  • the curve of FIG. 3 may be generated from information from the wind turbines about active power generated and voltage. This information may then be used to determine the capability of the wind turbines to deliver/consume reactive power.
  • FIG. 4 illustrates a further exemplary embodiment of a wind park 400 .
  • Eight wind turbines 401 to 408 are connected via transformers 409 to 416 to a common line, for example a cable.
  • a utility grid 417 is connected to the common line via a transformer 418 .
  • all eight wind turbines may deliver 0.6 MVAr in a normal operation.
  • the four wind turbines electrically closest to the delivery point of the grid i.e., the wind turbines 401 to 404
  • deliver 1.0 MVAr The operation in the second case corresponds to the operation as described herein when using the described capability scheme.
  • the wind turbines deliver 4.0 MVAr in total.
  • a Weibull wind distribution with factors 2 and 7 may be used to calculate the yearly losses.
  • the losses are reduced by 125 MWh when using the operation according to the herein described wind park control system.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

A wind park control system for controlling reactive power output of wind turbines is described. The wind park delivers active power and reactive power to a utility grid. A total amount of reactive power required by the utility grid and an individual amount of reactive power for each wind turbine are determined. A capability scheme having an order for selecting the wind turbines to deliver reactive power is calculated based on the individual amount of reactive power and the total electrical power loss contributed by each connection of the wind turbines to the utility grid. An actual amount of reactive power provided by the wind turbines is adjusted. The reactive power output of each wind turbine is controlled based on the capability scheme. The wind turbines are selected for delivering reactive power in the order of the capability scheme so that the total amount of reactive power is fulfilled.

Description

    CROSS REFERENCE TO RELATED APPLICATIONS
  • The present application claims priority to European Patent Office application No. 12178689.1 EP filed Jul. 31, 2012, the entire content of which is hereby incorporated herein by reference.
  • FIELD OF INVENTION
  • The present invention relates to the technical field of wind parks. In particular, the present invention relates to a control system for a wind park, in particular controlling the reactive power output of each wind turbine in the wind park.
  • BACKGROUND OF INVENTION
  • Wind parks comprise a plurality of single wind turbines and provide power to a utility grid. Today utility grids require reactive power delivery/consumption from wind power plants or parks. The reactive power may be needed for instance by loads (like electrical motors). Modern wind turbines may be able to control their reactive power output. Thus, the reactive power requirement of the utility grid may be fulfilled.
  • Typically, all wind turbines deliver or consume reactive power based on the same reference. Thereby, all wind turbines contribute with almost the same amount of reactive power. All wind turbines provide electrical loss to the overall system, however, some wind turbines give more electrical loss than other.
  • SUMMARY OF INVENTION
  • Therefore, there may be a need for an efficient and reliable control of the reactive power of the wind park to ensure that overall requirements are fulfilled and electrical losses are minimized.
  • This need may be met by the subject matter according to the independent claims. Advantageous embodiments of the present invention are described by the dependent claims.
  • According to a first aspect of the invention, there is provided a wind park control system for controlling a reactive power output of a plurality of wind turbines of a wind park, wherein the wind park is adapted to deliver active power and reactive power to a utility grid. The wind park control system comprises a determination unit being adapted to determine a total amount of reactive power being required by the utility grid (which corresponds to receiving information from the utility grid being indicative for the total amount of reactive power being required by the utility grid) and being adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver, a calculation unit being adapted to calculate a capability scheme, wherein the capability scheme comprises an order for the plurality of wind turbines according to which order the wind turbines are selected for delivering reactive power, wherein the capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and the total electrical power loss being contributed by each connection of all the wind turbines to the utility grid, and an adjustment unit being adapted to adjust an actual amount of reactive power to be provided by the plurality of wind turbines, wherein the reactive power output of each wind turbine is controlled based on the calculated capability scheme wherein the wind turbines are selected for delivering reactive power in the order of the capability scheme, such that the determined total amount of reactive power is fulfilled.
  • A wind park may comprise a plurality of wind turbines for delivering power to a utility grid. A wind turbine may be used for generating electrical power by converting wind into electrical power. Typically, wind turbines comprise a tower, a wind turbine rotor, which is arranged at a top portion of the tower and which comprises at least one blade, and a generator being mechanically coupled with the wind turbine rotor.
  • Based on an input power, the wind, the generator is able to convert the input power into electrical output power. The utility grid, to which power may be delivered, may have some requirements, in particular reactive power requirements, which should be fulfilled. These requirements may be provided to the wind park control system, in particular the determination unit. The utility grid may have specific requirements for the reactive power. The requirements for delivery/consumption of reactive power from the wind park or wind power plant may be either reactive power, power factor or voltage control.
  • To reduce the electrical losses, which may occur caused by the connection between a wind turbine and the connection point of the wind park and the utility grid, wind turbines contributing less electrical loss may be preferred for providing or delivering reactive power. The wind turbines may be selected according to the electrical loss they contribute and according to the amount of reactive power they may provide. The wind turbines may be selected in a number or amount sufficient for fulfilling the requirements for reactive power of the utility grid. Thus, the reactive power of the wind turbines may be accumulated.
  • The determination unit and the calculation unit may be integrated as one single unit. The plurality of wind turbines may be at least two wind turbines.
  • According to an embodiment of the invention, the determination unit is adapted to determine the individual amount of reactive power for each wind turbine based on a generated active power and a voltage at the wind turbine.
  • According to this embodiment, the reactive power each wind turbines is capable to deliver may be determined first. The determination may be based on an actual voltage and an actual active power generated at the wind turbine.
  • According to a further embodiment of the invention, the order of the wind turbines in the capability scheme is based on priorities, wherein a wind turbine having a connection with the lowest electrical loss has the highest priority. Thus, the wind turbine having the minimum electrical collector network power loss from all the wind turbines may have the highest priority.
  • The capability scheme may comprise a table wherein the wind turbines are arranged in an order corresponding to the amount of electrical loss they are providing. Hereby, the wind turbine contributing the lowest electrical loss may have the highest priority, wherein a wind turbine contributing more electrical loss may have a lower priority.
  • According to a further embodiment of the invention, the determination unit is adapted to determine the electrical losses based on a resistance being provided by the connection and a current being associated with the reactive power of the wind turbine.
  • The electrical loss each wind turbine is contributing may be determined based on characteristics of the connection. Each connection may have a specific resistance. The electrical loss may be calculated by the resistance of the connection multiplied with a current squared, wherein the current may consist of two parts, active current and reactive current. The current may be associated with the reactive power of the wind turbine.
  • According to a further embodiment of the invention, the order of the wind turbines in the capability scheme is based on priorities, wherein a priority is associated with the resistance being provided by the corresponding connection such that a low resistance is associated with a high priority.
  • The capability scheme may comprise a table wherein the wind turbines are arranged in an order corresponding to the amount of resistance of the corresponding connection. Hereby, the wind turbine having the connection with the lowest resistance may have the highest priority, wherein a wind turbine having a connection with a higher resistance may have a lower priority.
  • According to a further embodiment of the invention, the determination unit is further adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to consume, and the calculation unit is adapted to calculate the capability scheme based on the determined individual amount of reactive power of each wind turbine, which each wind turbine is capable to deliver and/or consume.
  • In addition to the capability of delivering reactive power, the determination unit may also determine the capability of each wind turbine to consume reactive power. The capability scheme may in this case comprise information about the capability of delivering and consuming reactive power for each wind turbine.
  • According to a further embodiment of the invention, the adjustment unit is further adapted to adjust the actual amount of reactive power to be provided by the plurality of wind turbines by controlling the reactive power output of each wind turbine based on the calculated capability scheme such that the wind turbines are selected for delivering and/or consuming reactive power to fulfill the determined total amount of reactive power.
  • In addition to delivering reactive power, each wind turbine may also consume reactive power. This may be used for adjusting the reactive power being needed by the utility grid.
  • According to a further aspect of the invention, a wind park is provided. The wind park comprises a wind park control system having the above mentioned features and a plurality of wind turbines being controllable by the wind park control system.
  • The wind park control system may be located near the wind turbines or may be located remote. Further, the wind park control system may be comprised by single units, each unit being located near a wind turbine.
  • According to a further aspect of the invention, a method for controlling a reactive power output of a plurality of wind turbines of a wind park is provided, wherein the wind park is adapted to deliver active power and reactive power to a utility grid. The method comprises determining, by a determination unit, a total amount of reactive power being required by the utility grid and determining for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver, calculating, by a calculation unit, a capability scheme, wherein the capability scheme comprises an order for the plurality of wind turbines, according to which order the wind turbines are selected for delivering reactive power, wherein the capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and the total electrical power loss being contributed by each connection of all the wind turbine to the utility grid, and adjusting, by an adjustment unit, an actual amount of reactive power to be provided by the plurality of wind turbines, wherein the reactive power output of each wind turbine is controlled based on the calculated capability scheme wherein the wind turbines are selected for delivering reactive power in the order of the capability scheme, such that the determined total amount of reactive power is fulfilled.
  • According to a further aspect of the invention, there is provided a computer program for controlling a reactive power output of a plurality of wind turbines of a wind park, the computer program, when being executed by a data processor, is adapted for controlling the method as described above.
  • According to a further aspect of the invention, there is provided a computer-readable medium, in which a computer program for controlling a reactive power output of a plurality of wind turbines of a wind park is stored, which computer program, when being executed by a processor, is adapted to carry out or control a method as described above.
  • As used herein, reference to a computer program is intended to be equivalent to a reference to a program element and/or a computer readable medium containing instructions for controlling a computer system to coordinate the performance of the above described method.
  • The computer program may be implemented as computer readable instruction code by use of any suitable programming language, such as, for example, JAVA, C++, and may be stored on a computer-readable medium (removable disk, volatile or non-volatile memory, embedded memory/processor, etc.). The instruction code is operable to program a computer or any other programmable device to carry out the intended functions. The computer program may be available from a network, such as the World Wide Web, from which it may be downloaded.
  • The herein disclosed subject matter may be realized by means of a computer program respectively software. However, the herein disclosed subject matter may also be realized by means of one or more specific electronic circuits respectively hardware. Furthermore, the herein disclosed subject matter may also be realized in a hybrid form, i.e. in a combination of software modules and hardware modules.
  • It has to be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments have been described with reference to apparatus type claims whereas other embodiments have been described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the apparatus type claims and features of the method type claims is considered as to be disclosed with this document.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • The aspects defined above and further aspects of the present invention are apparent from the examples of embodiments to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.
  • FIG. 1 shows a wind park comprising a wind park control system according to an embodiment of the present invention.
  • FIG. 2 shows a flow diagram for controlling a wind park according to a further embodiment of the invention.
  • FIG. 3 shows a capability scheme according to an embodiment of the invention.
  • FIG. 4 shows a wind park layout according to an embodiment of the invention.
  • DETAILED DESCRIPTION OF INVENTION
  • The illustration in the drawing is schematically. It is noted that in different figures, similar or identical elements are provided with the same reference signs.
  • FIG. 1 shows a wind park 100. The wind park 100 comprises a wind park control system 101 and a plurality of wind turbines 105, 106, 107. The wind park control system is adapted to control a reactive power output of the plurality of wind turbines. The wind park may deliver active power and reactive power to a utility grid (not shown).
  • The wind park control system comprises a determination unit 102, a calculation unit 103 and an adjustment unit 104. The determination unit 102 is adapted to determine a total amount of reactive power being required by the utility grid. The determination unit is further adapted to determine for each wind turbine an individual amount of reactive power, which the wind turbine is capable to deliver.
  • The calculation unit 103 is adapted to calculate a capability scheme. The capability scheme comprises an order for the plurality of wind turbines according to which the wind turbines are selected for delivering reactive power. The capability scheme is calculated based on the determined individual amount of reactive power of each wind turbine and an electrical loss occurring due to a connection from each wind turbine to the utility grid.
  • The adjustment unit 104 is adapted to adjust an actual amount of reactive power to be provided by the plurality of wind turbines. The reactive power output of each wind turbine is controlled based on the calculated capability scheme wherein the wind turbines are selected for delivering reactive power in the order of the capability scheme such that the determined total amount of reactive power is fulfilled.
  • FIG. 2 illustrates a flowchart for the function of the wind park control system. An amount of active power from all wind turbines 201 and an amount of voltage at all wind turbines 202 is provided to the calculation/determination unit 203. In this unit, the capability scheme is calculated and provided 204 to the adjustment unit 205. Here, the reactive power deliver from the wind turbines is adjusted according to the capability scheme. In a next step 206, it is determined whether the reactive power requirements 207 from the utility grid are fulfilled. If yes, it may be repeatedly determined whether the requirements are still fulfilled. If no, the adjustment may be repeated.
  • To reduce electrical losses in the electrical network of the wind power plant, the capability scheme may be set up so that the wind turbines that give the lowest losses in the network are used first to deliver/consume the reactive power. The capability scheme comprises information so that the turbines being electrical closest to the connection point of the wind farm/park to the utility grid are first used to deliver/consume the reactive power required by the utility grid.
  • FIG. 3 illustrates an example for a capability scheme according to an embodiment of the invention. The scheme is shown for eight wind turbines. On the x-axis, the numbers represent the wind turbines. On the y-axis, the accumulated reactive power from all wind turbines is shown. The wind turbine 1 is electrical closest to the connection point of the wind farm (i.e., contributes the lowest electrical loss) and then wind turbine 2 is the next and so on up to number 8. The wind turbine numbers are where the wind turbine is at their reactive power capacity. It may be assumed that each wind turbine can deliver/consume +/−1.0 pu (per-unit) reactive power in this example.
  • For example, if it is required that the wind turbines deliver 4.5 pu reactive power, then wind turbine 1, 2, 3 and 4 have to deliver their full reactive power of 1.0 pu and wind turbine 5 has to deliver 0.5 pu. If there is a change in the reactive power requirement, then the control system should follow the curve to have a jumpless transfer between two reactive power setpoints.
  • In a real wind farm, the curve of FIG. 3 may be generated from information from the wind turbines about their capability to deliver/consume reactive power. This capability may be typically dependent on active power generated and voltage at the wind turbines. The active power and voltage from each wind turbine may be send to the determination/calculation unit, which then calculates the capabilities for deliver/consume reactive power.
  • The electrical losses in the wind farm network are related to the resistance time the current squared. The current may consist of two parts, one is active current and the other is reactive current. One idea of the present system is to prioritize the reactive current. This means that the reactive current may run through a minimum if resistance. Further, the control system may follow the line of FIG. 3 to give a jumpless transfer between two reactive power setpoints. Further, the curve of FIG. 3 may be generated from information from the wind turbines about active power generated and voltage. This information may then be used to determine the capability of the wind turbines to deliver/consume reactive power.
  • FIG. 4 illustrates a further exemplary embodiment of a wind park 400. Eight wind turbines 401 to 408 are connected via transformers 409 to 416 to a common line, for example a cable. A utility grid 417 is connected to the common line via a transformer 418.
  • In one case, all eight wind turbines may deliver 0.6 MVAr in a normal operation. In a second case, the four wind turbines electrically closest to the delivery point of the grid (i.e., the wind turbines 401 to 404) deliver 1.0 MVAr. The operation in the second case corresponds to the operation as described herein when using the described capability scheme. In both scenarios, the wind turbines deliver 4.0 MVAr in total.
  • A Weibull wind distribution with factors 2 and 7 may be used to calculate the yearly losses. When comparing the network losses in the two scenarios, the losses are reduced by 125 MWh when using the operation according to the herein described wind park control system.
  • It should be noted that the term “comprising” does not exclude other elements or steps and “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

Claims (9)

1. A wind park control system for controlling a reactive power output of a plurality of wind turbines of a wind park to deliver an active power and a reactive power to a utility grid, comprising:
a determination unit adapted to determine a total amount of reactive power required by the utility grid and to determine an individual amount of reactive power for each wind turbine being capable to deliver;
a calculation unit adapted to calculate a capability scheme for selecting the wind turbines according to an order to deliver the reactive power, wherein the capability scheme is calculated based on the individual amount of reactive power and a total electrical power loss contributed by connections of the wind turbines to the utility grid; and
an adjustment unit adapted to adjust an actual amount of reactive power provided by the wind turbines,
wherein a reactive power output of each wind turbine is controlled based on the capability scheme, and
wherein the wind turbines are selected based on the order of the capability scheme to fulfill the total amount of reactive power.
2. The wind park control system according to claim 1, wherein the determination unit is adapted to determine the individual amount of reactive power for each wind turbine based on a generated active power and a voltage at the each wind turbine.
3. The wind park control system according to claim 1, wherein the order in the capability scheme for selecting the wind turbines is based on priorities, and wherein a wind turbine having a connection with a lowest electrical loss has a highest priority.
4. The wind park control system according to claim 1, wherein the determination unit is adapted to determine an individual electrical power loss based on a resistance provided by connection of each wind turbine and a current associated with the reactive power of each wind turbine.
5. The wind park control system according to claim 4, wherein the order in the capability scheme for selecting the wind turbines is based on priorities, wherein a priority is associated with the resistance provided by the connection so that a low resistance is associated with a high priority.
6. The wind park control system according to claim 1,
wherein the determination unit is adapted to determine an individual amount of reactive power for each wind turbine being capable to consume, and
wherein the calculation unit is adapted to calculate the capability scheme based on the individual amount of reactive power of each wind turbine being capable to deliver and/or consume.
7. The wind park control system according to claim 1, wherein the adjustment unit is adapted to adjust the actual amount of reactive power provided by the wind turbines by controlling the reactive power output of each wind turbine based on the capability scheme so that the wind turbines are selected for delivering and/or consuming reactive power to fulfill the total amount of reactive power.
8. A method for controlling a reactive power output of a plurality of wind turbines of a wind park to deliver an active power and a reactive power to a utility grid, comprising:
determining a total amount of reactive power required by the utility grid and determining an individual amount of reactive power for each wind turbine being cable to deliver by a determination unit;
calculating a capability scheme by a calculation unit for selecting the wind turbines according to an order to deliver the reactive power, wherein the capability scheme is calculated based on the individual amount of reactive power and a total electrical power loss contributed by connections of the wind turbines to the utility grid; and
adjusting an actual amount of reactive power provided by the wind turbines by an adjustment unit;
controlling a reactive power output of each wind turbine based on the capability scheme; and
selecting the wind turbines based on the order in the capability scheme to fulfill the total amount of reactive power.
9. A computer-readable medium, comprising:
a computer program stored in the computer-readable medium for controlling a reactive power output of a plurality of wind turbines of a wind park to deliver an active power and a reactive power to a utility grid,
wherein the computer program is executed by a processor to perform a method as claimed in claim 8.
US13/951,705 2012-07-31 2013-07-26 Wind park control system Abandoned US20140035284A1 (en)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130257050A1 (en) * 2012-03-27 2013-10-03 John Bech Method for controlling a wind farm, wind farm controller, wind farm, computer-readable medium and program element
US20150061290A1 (en) * 2013-09-05 2015-03-05 General Electric Company System and method for voltage control of wind generators
US20150130187A1 (en) * 2013-11-11 2015-05-14 Siemens Aktiengesellschaft Method of operating a wind park
US9447772B2 (en) 2014-12-18 2016-09-20 General Electric Company Systems and methods for increasing wind turbine power output
EP3146609A1 (en) * 2014-07-21 2017-03-29 Siemens Aktiengesellschaft Multi-generator power plant arrangement, energy supply network having a multi-generator power plant arrangement, and method for distributing reactive power generation in a multi-generator power plant arrangement
DE102016009413A1 (en) * 2016-08-04 2018-02-08 Senvion Gmbh Method for controlling the reactive power output of a wind farm and a corresponding wind farm
US10240586B2 (en) 2016-01-29 2019-03-26 Siemens Aktiengesellschaft Operating a wind turbine of a wind farm
US10320196B2 (en) * 2013-12-11 2019-06-11 Vestas Wind Systems A/S Wind power plant, and a method for increasing the reactive power capability of a wind power plant

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106537717B (en) 2014-05-30 2020-02-14 维斯塔斯风力系统有限公司 Method for controlling a wind power plant, wind power plant system and storage medium
EP3204996A1 (en) 2014-10-07 2017-08-16 Vestas Wind Systems A/S Reactive power support from wind turbine facilities
GB2565308B (en) 2017-08-08 2020-06-24 British Gas Trading Ltd System for controlling energy supply across multiple generation sites
CN109347122B (en) * 2018-11-21 2022-01-25 国电联合动力技术有限公司 Intelligent control method and system for participating in active power regulation of wind power plant sample board machine

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090121483A1 (en) * 2007-11-13 2009-05-14 Qimou Xiong Methods and systems for wind turbine generators
US20090218817A1 (en) * 2008-02-28 2009-09-03 General Electric Company Windfarm collector system loss optimization
US20100025994A1 (en) * 2008-07-29 2010-02-04 General Electric Company Intra-area master reactive controller for tightly coupled windfarms
US8290634B2 (en) * 2008-10-09 2012-10-16 General Electric Company Optimizing system loss for a system of multiple windfarms
US20130168963A1 (en) * 2010-08-31 2013-07-04 Jorge Martinez Garcia Control of electric output of a wind park
US20130175800A1 (en) * 2010-12-29 2013-07-11 Repower Systems Se Wind farm and method for operating a wind farm
US20140062086A1 (en) * 2010-08-02 2014-03-06 Alstom Wind, S.L.U. Reactive Power Regulation

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2221957B1 (en) * 2007-12-14 2017-11-01 Mitsubishi Heavy Industries, Ltd. Wind power generation system and its operation control method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090121483A1 (en) * 2007-11-13 2009-05-14 Qimou Xiong Methods and systems for wind turbine generators
US20090218817A1 (en) * 2008-02-28 2009-09-03 General Electric Company Windfarm collector system loss optimization
US20100025994A1 (en) * 2008-07-29 2010-02-04 General Electric Company Intra-area master reactive controller for tightly coupled windfarms
US8290634B2 (en) * 2008-10-09 2012-10-16 General Electric Company Optimizing system loss for a system of multiple windfarms
US20140062086A1 (en) * 2010-08-02 2014-03-06 Alstom Wind, S.L.U. Reactive Power Regulation
US20130168963A1 (en) * 2010-08-31 2013-07-04 Jorge Martinez Garcia Control of electric output of a wind park
US20130175800A1 (en) * 2010-12-29 2013-07-11 Repower Systems Se Wind farm and method for operating a wind farm

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130257050A1 (en) * 2012-03-27 2013-10-03 John Bech Method for controlling a wind farm, wind farm controller, wind farm, computer-readable medium and program element
US8901764B2 (en) * 2012-03-27 2014-12-02 Siemens Aktiengesellschaft Method for controlling a wind farm, wind farm controller, wind farm, computer-readable medium and program element
US20150061290A1 (en) * 2013-09-05 2015-03-05 General Electric Company System and method for voltage control of wind generators
US9318988B2 (en) * 2013-09-05 2016-04-19 General Electric Company System and method for voltage control of wind generators
US20150130187A1 (en) * 2013-11-11 2015-05-14 Siemens Aktiengesellschaft Method of operating a wind park
US9541063B2 (en) * 2013-11-11 2017-01-10 Siemens Aktiengesellschaft Method of operating a wind park
US10320196B2 (en) * 2013-12-11 2019-06-11 Vestas Wind Systems A/S Wind power plant, and a method for increasing the reactive power capability of a wind power plant
EP3146609A1 (en) * 2014-07-21 2017-03-29 Siemens Aktiengesellschaft Multi-generator power plant arrangement, energy supply network having a multi-generator power plant arrangement, and method for distributing reactive power generation in a multi-generator power plant arrangement
US9447772B2 (en) 2014-12-18 2016-09-20 General Electric Company Systems and methods for increasing wind turbine power output
US10240586B2 (en) 2016-01-29 2019-03-26 Siemens Aktiengesellschaft Operating a wind turbine of a wind farm
DE102016009413A1 (en) * 2016-08-04 2018-02-08 Senvion Gmbh Method for controlling the reactive power output of a wind farm and a corresponding wind farm

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DK2693589T3 (en) 2015-03-09

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